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Merge pull request #46336 from Infinisil/overrideExisting

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lib: Improve overrideExisting implementation
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Jörg Thalheim 2018-09-18 11:37:30 +01:00 committed by GitHub
parent 7d39e99a1e c7104d97c8
commit 83d89edc6e
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2 changed files with 21 additions and 4 deletions
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11
lib/attrsets.nix
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@ -435,12 +435,15 @@ rec {
useful for deep-overriding.
Example:
x = { a = { b = 4; c = 3; }; }
overrideExisting x { a = { b = 6; d = 2; }; }
=> { a = { b = 6; d = 2; }; }
overrideExisting {} { a = 1; }
=> {}
overrideExisting { b = 2; } { a = 1; }
=> { b = 2; }
overrideExisting { a = 3; b = 2; } { a = 1; }
=> { a = 1; b = 2; }
*/
overrideExisting = old: new:
old // listToAttrs (map (attr: nameValuePair attr (attrByPath [attr] old.${attr} new)) (attrNames old));
mapAttrs (name: value: new.${name} or value) old;
/* Get a package output.
If no output is found, fallback to `.out` and then to the default.

14
lib/tests/misc.nix
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@ -236,6 +236,20 @@ runTests {
};
};
testOverrideExistingEmpty = {
expr = overrideExisting {} { a = 1; };
expected = {};
};
testOverrideExistingDisjoint = {
expr = overrideExisting { b = 2; } { a = 1; };
expected = { b = 2; };
};
testOverrideExistingOverride = {
expr = overrideExisting { a = 3; b = 2; } { a = 1; };
expected = { a = 1; b = 2; };
};
# GENERATORS
# these tests assume attributes are converted to lists